Silicon photonics can be defined as the use of silicon-based materials for the generation, guidance, control, and detection of light to communicate information over distance. When you use a laser to produce light, the output is a continuous wave. So you need an optical modulator to encode data for use in an optical communications link. Current optical modulators run at around 20 MHz, but PhysOrg.com says that in a technological breakthrough in silicon photonics, "Intel Silicon-based Optical Modulator Could Run Faster Than 1GHz." As these modulators can be made out of silicon by using current manufacturing processes, this advance paves the way to a future production of photonics products based on silicon.
Here is the introduction of this article.
Intel researchers have developed a silicon-based optical modulator operating at 1GHz -- an increase of over 50 times the previous research record of about 20MHz. Fabricated in an Intel Fab using Intel's existing high-volume manufacturing processes, the device incorporates a transistor-like structure to encode data onto a wavelength of light.
Intel's breakthrough modulator takes an incoming light beam and splits it into two beams. The beams are then "phase shifted" relative to each other to change the amplitude of the resulting, recombined beam. The result is the ability to change light from bright to dark and thus encode data.
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Here is a diagram showing a Mach-Zehnder interferometer (MZI) modulator with two phase shifter sections (Credit: Intel Corporation). |
What can we expect from these new optical modulators?
By demonstrating how optical modulators can be made out of silicon using Intel's standard manufacturing processes in an existing fab, Intel researchers have removed a significant cost barrier in photonics. The next step is integrating entire photonic devices on a chip with digital intelligence. This should pave the way to produce photonics products based on silicon.
Intel expects to achieve even greater bandwidth in silicon photonic devices by multiplexing many data streams onto multiple wavelengths of light onto one optical fiber. This approach could bring silicon photonics into an age where enormous amounts of data can be exchanged at high speeds on a single fiber.
For far more technical information about this discovery, let's turn to Intel Technology Journal who published a special series of articles about silicon photonics in May 2004. Here is a link to the abstract about Silicon Photonics.
We introduce our approach to opto-electronic integration, silicon photonics, and outline the key functions required for an opto-electronic integration platform: generation, control, and detection of light. Recent research results for silicon-based optical components are discussed including a tunable external cavity laser, a 2.5 GHz optical modulator and a silicon-germanium waveguide-based photodetector. Lastly, optical packaging challenges and potential next-generation designs are presented.
And here is a link to the optical modulator. Here is a short excerpt of the conclusion.
Our modulator with MOS capacitor phase shifters has demonstrated bandwidth performance previously unseen in silicon modulators, and modeling suggests that high-speed modulation at 10 GHz is achievable with design optimization.
Sources: PhysOrg.com, July 14, 2004; Intel Technology Journal, Volume 8, Issue 2, May 10, 2004
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